Compressor rotor



April 5, 1960 H. LECHTHALER ETAL 2,931,625

COMPRESSOR ROTOR Filed Dec. 17, 1956 f 2 Sheets-sheet 1 April 5, 1960 Filed D60. 17, 1956 L. H. LECHTHALER ETAL COMPRESSOR Ro'roR 2 Sheets-Sheet 2 COMPRESSOR noroR Application December 17, 1956, Serial No. 628,682

Claims. (Cl. 253-77) The present invention relates to rotors for compressors or the like and more particularly to rotors for axial flow type compressors used in small turbo engines for aircraft. More specifically, the invention relates to such a rotor in which the compressor blades are individually attachable to and detachable from the rotor.

An object of the present invention is to provide such a rotor in which the time, skill and labor involved in attaching and detaching the individual blades is reduced to a minimum, in which the blades can be attached and detached without the necessity of utilizing complicated accessory too'ls such as turn tables,V means for measuring run outs and parallelism, etc., in which the conventional and complicated blade coupling and fastening elements such as discs, top rings, splines, anges, a plurality of bolts, etc., are eliminated and which is simple in construction and has a minimum number of separate parts.

A further object is to provide such a rotor in which the compressor blades can beindividually attached and detached without the necessity of disassembling the rotor from its installation.

A still further object is to provide such a rotor'in which the blades can be attached and detached without removing any parts other than the blades, in which the only parts which must be handled other than the blades in disassembling and assembling the blades comprises a simple, inexpensive locking member for each row of blades, such member being easily accessible while the rotor is installed, and in which the only manipulation other than movement of the blades themselves required to assemble and disassemble the blades of each row is a simple turning movement of the single locking member.

Another further object is to provide such a rotor which is simple and inexpensive to assemble, disassemble, service and manufacture but yet which isrugged and'durable and requires a minimum of maintenance. Because of its simplicity in construction and the small number of parts, it is more stable so that there is less likelihood of unbalance, and hence less correction is required, than in conventional built up rotor designs. Its simplicity and small number of parts also eliminates a large factor in the stack up of tolerances usually present in conventional built up blade arragements so that smaller radial and axial clearances are possible.

Another still further object is to provide such a rotor in which the locking mechanism for locking the blades in attached position is locked against accidental removal when the blades are assembled and is urged into locking position by the centrifugal force of the rotating rotor. The above cited economies of manufacture, assembly and service of the rotor of the present inventionmakes it ideally suitable for volume production.

. r The construction of the present inventionis particularly suitable for small turbo engines of the type described in application Serial No. 548,987, tiled by G. W. Lawson on November 25, 1955, now Patent No. 2,912,823, and assigned to the same assignee of the present application.

The above and other ,objectsV are effected bythe presnited States Patent O 2,931,625 Patentedv Apr. 5, 1960 ICC ent invention as will be apparent from the following description and claims and the accompanying drawings, all of which describe and show by way of illustration only and without limitation, what is now considered to be the preferred embodiment of the invention.

In the drawings:

Fig. l is a cross section in elevation of a portion of a rotor embodying the present invention'.

Fig. 2 is a plan View of a portion of the roto-r of Fig. l.

Fig. 3 is an enlarged view of the locking mechanism of Fig. 2.

Fig. 4 is a view taken along the line 4--4 of Fig. 2.

Fig. 5 is a plan view showing the entry slot.

Fig. 6 is a vieu/.taken along the line 6-6 of Fig. 2 with the portion of the blade holding member between the line 6--6 and the blade holding slot being cut away and sho-wing only two adjacent blades.

Fig. 7 is an enlarged view of one of the blades of Fig. l.A

Fig. 8 is a view showing one of two locking blades of Fig. 2, and showing the shape of the entry slot.

Referring more particularly to the figures, 1 is a generally cylindrically shaped, hollow spool or drum onev which extend therearound and which` also extend inwardly intointernal annular ribs 9.

The periphery of spool 1 has a plurality of blade hold,

ing dove tail shaped slots'10 extending circumferentially therearound, each slot 10 extending into the thickened portion 8 and lying in a plane which is perpendicular to the longitudinal center line of the spool. Each slot 10 (see Figs. 4 and 6) comprises a lower, wider portion 11 which extends upwardly into a narrow neck 13, which diverges outwardly at 15 as shown. Each slot 10 slidably receives the dove tail shaped roots 14 of a plurality of Vblades 12, 12a, and 12b. Each root 14 has a widened lower portion 11a which is received by portion 11 of the slot, a narrow neck portion 13a received by the narerow neck portion 13 of the slot, and an upwardly diverg-4 ing portion 15a, which is received by the diverging portion 15 of the slot. The upwardly flared portion 15a of each root extends upwardly into a at, substantially rectangular shaped platform 16 or 16a which in turn extends upwardly into a blade portion 18. Some of the end walls 20 of platforms 16 are beveled and some are not dependingV on the position which the blade occupies on the member 1. The circumferential width b of root 14 (see Figs. 2 and 6) is about 50% of the circumferential width of end wall 20 of the platforms.

The top ared out portions 15 of the slot 10 are shaped or counter sunk to receive the platforms 16 so that the top of the platforms are flush with the periphery of the drum. The adjacent side edges 22 of the platforms 16 or 16a abut each other when all the blades are assembled as shown so that sliding movement of each blade in the slot with relation to the other blade is prevented and sliding movement of one blade in the slot causes all the blades to be moved as a unit. p v

The roots 14 are inserted into blade holding slot 10 by means of an entry slot 24, see Figure 5, which is sufficiently wider than the blade holding slot 10 and the wide* portions 13a of the roots to permit them to'be inserted of the slot 10.

The top flared out parts 15 of the end portions of slot 10 adjacent`j entry slot 24 (see Figs. 2, 4,'5, and 6) extend laterally in one direction further than the top flared out part 15 of the rest of the slot 10 to form a rabbet or recess 28 in member 1. One end 27 of the rabbet is curvilinear in shape and the other endA forms a shoulder 32.

"When all the blades are assembled in the slots 10 (see Fig. and 24, as shown, with their side edges 22 abutting against each other, the root and platform of the blade 12a extends partially into the end portion 26a of slot and partially into entry slot 24, and the root and platform ofthe blade 12b extends partially into the other end portion 26 of slot 10 and partially into entry slot 24. The adjacent side edges 22 of blades 12a andV 12b abut against each other (Fig. 6,).

The platforms 16a of these two blades 12a and 12b are greater in axial width than the platforms 16 of the other blades and extend laterally at 30a beyondthe bases of their blade portions 18 into the rabbet 28. As shown in Figs. 4 and 8 the rabbet is contoured to snugly receive these laterally extending portions 30a so that the surfaces of the platforms 16a are llush with the periphery of spool 1 just like the top surfaces of the other platforms 16. Except for these laterally extending portions 30a of platforms 16a, blades 12a and 12b are similar to the other blades 12. v

The laterally extending portions 30a of platforms 16a are locked between the shoulder 32 of rabbet 28, against which the side edge 30 of widened portion 30a of blade 12a abuts, and a narrow shankV portion 34 of set screw 35 which engages the edge 36 of portion 30a of blade 12b and which protrudes from the threaded aperture 40 in spool 1 into the rabbet. The threaded aperture 40 is deep enough so that the screw 35 can be fully retracted into it, including the'shank portion 34, whereby the portions 30a are no longer locked against movement( in rabbet 2 8 and the blades can be removed and inserted in the slot 10 as hereinafter described.

When the blades are assembled, as shown in Fig. 2, the edge 36 of blade 12b overlies a portion of the aperture 40 and thereby engages the shoulder 44 formed between shank 34 and threads 38 of screw 35 when the screw is moved out of its aperture to its locking position shown in Fig. 6, whereby accidental removal of the screw from the aperture is prevented.

Since, when the blades are assembled as shown, the sides 22 of the platforms 16 and 16a of all the blades 10 a suicient distance before edge 36 abuts against the end 27 of the slot, to" permit the insertion of the root and platform of yblade 12a into the entry slot 24 and rabbet 28, the side edges 22 of its platform 16a fitting snugly between the side edges 22 of the platforms of adjacent blade 12, and blade 12b. Thereafter portions 30a are moved in rabbet 28 toward shoulder 32 until the edge 30 engages the shoulder 32. At the same time all theblades slide in slots 10 and 24 as a body to the position shown in Fig. 2 in which'theA roots of 12a and 12b are located partially in slot 24 and partially in the end portions of slot 10. After the blades and portions 30a have been moved to this position the screw 35 is screwed out of aperture 40'by means of a screw driver or simliar means until the shoulder 44 abuts against the bottom of that part of 30a of blade 12b overlying the aperture.

The blades are now assembled and the rotor is ready for use.

By merely screwing the screw35 into the aperture until it is completely retracted all the blades in slots 10 and 24 can be removed from the slot as described above.

` During rotation of the rotorV centrifugal force urges the screw 35 in a locking direction out of aperture 40 abut against each other so that one cannot be moved inslots 10 arid 24 without moving all of them, and byl locking portions 30a against movement in rab'Jet 23, all the blades in slots 10 and 24 are locked against sliding'movement therein and hence are effectively locked .into attached position by the single screw 35.

The rabbet 28 is long enough so that when the scre 35 is fully retracted into aperture 4t) the portions 30a can be moved into the rabbet a Vsufficient distance toward end 27 to permit the root of blade 12a to clear the end 26a of slot 10 and move entirely into entry slot 24, whereafter blade 12a can be lifted out of the entry slot.' Subsequently, the rest of the blades can be removed by sliding their roots into entry slot 24 and lifting them out of the entry slot. Movement of the portions 30a in rabbet 28 to move the root of 12a into entry slot 24 causes the entire row of blades to slide as a unit in slots 10 and 24 and thereby causes the root of blade 12b to move further into the end 26 of slot 10.

` The blades are assembled by individually inserting the roots of all the blades 12 into the slot 10 via the entry slot 24 while the screw 35 is retracted into the aperture 4Q, Thereafter, the root of blade 12b is inserted into `the end 26 of the slot 10 via entry slot 24 and moved into the slot until the edge 36 of portion 30a thereof abuts against end27-of rabbet 28. The rabbet 2S is long enough so that the blade 12b can be moved into slot and consequently urges shoulder 44 into engagement with the underside of that part of portion 30aV of bladc 12b which overlies the aperture.

The compressor blades rotate between stator vanes 18a xedly attached to the stator casing.

The rotor of the present invention is made up only of the rotor drum,'a screw for each slot and the blades. The only tool necessary to attach and detach the blades is an Allen wrench or screw driver, which can be used to screw and unscrew the screw into and out of aperture 40. The blades can be attached and detached without disassembliag the rotor from its installation and without the removal of any part from the rotor other than blades. To replace a defective blade it is necessary only to unlock the row in which the blade is located. The defective blade ca n be replaced while the rotor is installed and without handling any of the blades other than those in the row in which the defective blade is located.

What we claim as new and desire to secure by Letters Patent of the United States:

1. A rotor for axial ow compressors or the like comprising a generally cylindrical shaped blade holding member having at least one dove-tail shaped blade holding slot in the periphery thereof, a plurality of blades, each of said blades formed with a dove-tail root slidably received by said blade holding slot, the blade holding slot and root being vsuch that the root is locked against movement with respect to said blade holding slot other than sliding movement longitudinally along the blade holding slot, said member having a rabbet recess formed in a longitudinal edge of said slot, an entry slot formed in said blade holding slot along said rabbet recess for insertion and removal of said roots into said blade holding slot, at least one of said blades having an extension extending into said rabbet and slidable into abutment upon an edge thereof to l :event sliding movement of said roots inV one direction along said blade holding slot, and locking means extending from said blade holding member for locking said extension against movement in a second direction longitudinally along said slot to prevent movement of said roots to said entry slot, whereby all the lroots in said slot are locked against removal from said blade holding slot. 5

2. A rotor for an axial flow compressor comprising a blade holding member having at least one dove-tail shaped blade holding slot extending around the periphery thereof, a plurality of blades having dove-tail root portions thereon slidably received in said slot, the dove-tail shape of said slot yand said root portions being such as to restrain said root portions against radial movement relative to*4 said blade holding member, an entry slot extending intorsaid blade holding slot to permit insertion and removal of'saidfblade roots into and from said blade holding slot, a recess in said blade holding member positioned laterally adjacent said entry slot, portions of two of said blades extending laterally into said recess, an aperture in said recess, and a locking member having a narrow head portion and a base portion mounted in said aperture and extending radially therefrom, said locking member being adjustable radially inward to permit insertion and removal of said blade roots through said entry slot and adjustable radially outward to bring the shoulder between said narrow head portion and said base portion into engagement with the underside-of the laterally extending portion of one of said twov blades, thereby positioning said narrow head portion along an edge of said laterallyextending portionV to lock said laterally extending portions of said two blades between said narrow head portion and a shoulder of said recess.

3. A bladed rotor for accommodating axial uid ow therethrough comprising a blade holding member, a dovetail shaped blade holding slot extending around the pe riphery of said blade holding member, a plurality of blades each having a dove-tail root portion thereon, the root portion of each of said blades being slidably received in said slot, the dove-tail shapeof said slot and said blade roots being such that the roots are restrained against radial movement with respect to said blade holding member, an entry slot extending into said blade holding slot to permit insertion and removal of said blade roots into and from said blade holding slot, a laterally extending recess in said blade holding member adjacentsaid entry slot, at least one of said blades having a laterally extending portion thereon extending into said recess when said blades are assembled in said blade holding slot, and a locking member mounted in said recess and engaging the portion of said blade extending into said recess to restrain peripheral movement of said blades in one direction.

4. A bladed rotor as set fores in claim 3 wherein said locking member is radially threaded into an aperture in said recess to permit radial adjustment of said locking member into and out of locking engagement with the portion of said blade extending into said recess, said locking member having a portion thereon engageable with the underside of said laterally extending blade portion when said locking member is in the locking position.

5. A rotor for axial ilow compressors or the like comprising a blade holding member having at least one dovetailYV shaped blade holding slot extending around the periphery thereof, a plurality of blades each having a dove-tail root, each of said roots slidably received by said blade holding slot, the shape of said blade holding slot and said roots being such that said roots are locked against movement with respect to said slot other than sliding movement longitudinally in said slot, an entry slot extending into said blade holding slot for inserting and removing said roots into and from said blade hold- `ing slot, a first portion of the root of at least one of said blades extending into said entry slot and a second portion thereof extending into said blade holding slot when said rotor is in an assembled state, and means for locking said blades against removalv from and sliding movement in said blade holdingslot, said last mentioned means comprising a locking member extending from said blade holding member into engagement with iirst portion of said oneof said blades to prevent movement of said second portion ther-of into said entry slot, whereby said blades are locked against removal from said blade holding slot; said locking member being retractable into said member out of locking engagement with said rst portion, whereby said blades can 'be individually removed from and inserted into said entry slot and said blade holding slot.

References Cited in the file of this patent UNITED STATES PATENTS 672,838 Hodgkinson Apr. 23, 1901 1,010,630 Hodgkinson Dec. 5, 1911 1,687,891 Ray Oct. 16, 1928 1,705,585 Ray Mar. 19. 1929 2,315,631 Lloyd et al. Apr. 6, 1943 2,393,447 Allen Jan. 22, 1946 2,434,935 Kroon Ian.' 27, 1948 2,619,318 Schaer y.- Nov. 25, 1952 2,667,327 Hardigg Jan. 26, 1954 y FOREIGN PATENTS 560,951 Germany Oct. 8, 1932 

